This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-169227, filed Jun. 6, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a pivottable connection configuration of a retractable roof mounted antenna, especially for an automobile.
2. Description of the Related Art
FIG. 1 illustrates a conventional retractable automobile roof mounted antenna 10. FIG. 1 shows an antenna rod 11, an antenna base 12, a coaxial cable 13 extending from the bottom face of the antenna base, and a connecting plug 14 provided to the end portion of the coaxial cable 13 so as to connect the antenna with a tuner of the automobile on which the antenna is mounted.
As shown in FIG. 1, the antenna rod 11 has a retractable configuration that can be fixed at three positions, i.e., at 0xc2x0, 60xc2x0, and 180xc2x0 to the antenna base 12. The antenna rod 11 is configured such that a user can feel proper click resistance so as to firmly fix the antenna rod at respective positions.
FIG. 2 illustrates the specific structure for giving the click resistance to the roof mounted antenna shown in FIG. 1, especially to the pivottable connection member thereof.
The antenna rod 11 shown in FIG. 2 is provided at the proximal end portion with a cylindrical joint assembly 21 the axis direction of which is orthogonal to the axis direction of the antenna rod 11. The joint assembly 21 of the antenna rod 11 is engaged to the upper portion of the antenna base 12 so as to fix it to the antenna base by integrally fastening them with a bolt 22 or the like.
More specifically, one end portion (the left side portion shown in the illustration) of the joint assembly 21 has a terminal formed of a metal plate as a cover thereof. The terminal moves and contacts a terminal member 12b (described later) provided to the antenna base 12 so as to be electrically connected to the terminal member 12b. A coil spring 23 is to be introduced into an opening on the side of the other one end portion of the joint assembly 21 through a washer 24 in order to hold a click case assembly 25 in the joint assembly 21.
The upper portion of the antenna base 12 has a pair of banks so as to place the antenna base 12 therebetween. One of the banks (the right side portion shown in the illustration) has a hexagonal hole 12a in the wall thereof. Another one of the banks (the left side portion shown in the illustration) is formed as a terminal 12b having a hole formed in a size such that the bolt 22 can pass through it.
The joint assembly 21 is placed between the pair of the banks such that an O-ring 26 is held between the terminal 12b and the joint assembly 21. In this condition, the click case assembly 25 holding the spring 23 and the washer 24 therein is put into the joint assembly 21 from the outside of the hexagonal hole 12a. A bolt 22 having a hexagonal click plate 27 to penetrate it is introduced into the hexagonal hole 12a of the antenna base 12 from the outside to pass through the pair of the banks. The end tip of the bolt 22 projecting from the wall of the bank as the terminal 12b of the antenna base 12 is fastened with a nut 30 via a washer 28 and a spring washer 29 to fix it. By fabricating the components in this manner, the antenna rod 11 and the antenna base 12 can be integrally assembled.
The click case assembly 25 has recesses and convexes on the outer surface to be engaged with the recesses and convexes formed on the inner wall of the joint assembly 21. With this structure, the click case assembly is prevented from rotating in the circumferential direction.
In the same manner, the click plate 27 is also prevented by its own hexagonal shape from rotating in the circumferential direction, although it moves in the hexagonal hole 12a in the axis.
As shown in FIG. 3, the click case assembly 25 has a hole 251 formed by pressing in the central portion of the outer face of the bottom on which the click case assembly 25 contacts the click plate 27, such that the bolt 22 passes through it. A plate 25 having a pair of hemispherical convex portions 252 and 252 spaced apart by 180xc2x0 and opposing across the hole 251 is put into the bottom of the click assembly 25.
On the other hand, the click plate 27 contacting the plate 25a of the click case assembly 25, more precisely, comprises the hexagonal plate and a disk the circumference to inscribe the hexagonal circumference of the plate, which are integrally formed. To illustrate the more specific structure of the disk, the disk face contacting the click assembly 25 is shown in FIG. 3. As shown in the drawing, the disk is made of a cut thick aluminum plate, i.e., so-called cutout. The disk has a hole 271 in the central portion so as to introduce the bolt 22, and two pairs of grooves 272 and 272, 273 and 273, respectively spaced apart by 180xc2x0 and opposing across the hole 271. The grooves 272 and 272 and the grooves 273 and 273 are shifted from each other by 60xc2x0 as a central angle on the hole 271 as a center.
With the above-mentioned structure, in contacting the plate 25a of the click case assembly 25 with the click plate 27, the convex portions 252 and 252 of the click case assembly 25 shift to either of the grooves 272 and 272 and the grooves 273 and 273 due to the rotation of the antenna rod 11. In this manner, the convex portions 252 and 252 of the click case assembly 25 are engaged with either of the grooves 272 and 272 and the grooves 273 and 273, to generate the click resistance.
By virtue of this structure, the contacting force between the plate 25a of the click case assembly 25 and the click plate 27, and the contacting force between the terminal 12b of the antenna base 12 and the joint assembly holding the O-ring 26 therebetween are adjusted by the elasticity of the coil spring 23 in accordance with the fastening force of the nut 30 fastening the bolt 22. The click torque and the electric connection between the terminals thus depend on the adjustment of the contacting forces.
With the above-mentioned pivottable connection configuration of the retractable roof mounted antenna 10, the click torque according to the elasticity of the coil spring 23 and the fastening force of the nut 30 is generated by engaging the convex portions 252 and 252 formed in the plate 25a of the click case assembly 25 and the grooves 272 and 272 and the grooves 273 and 273 in the click plate 27 fixed to the hexagonal hole 12a of the antenna base 12.
FIG. 4 shows the rear side of the joint assembly 21, which is not shown in FIG. 2. A terminal face 21a on which the joint assembly 21 contacts the terminal 12b has a plurality of, e.g., three hemispherical convex portions 211, 211, and 211 formed to strengthen the electric connection. The click torque is also generated between the hemispherical convex portions 211, 211, and 211 and the terminal 12b of the antenna base 12. The hemispherical convex portions 211, 211, and 211 frictionally contact and slides on the terminal 12b to connect with the terminal 12b. By this connection, the antenna signal obtained by the antenna rod 11 is transmitted to the coaxial cable 13 via the antenna base 12.
With this structure, however, the portion for generating the click torque and the portion for transmitting the antenna signal need to be formed in different manufacturing processes. Especially, the click plate 27 is formed by cutting, which increases the manufacturing cost thereof, and the manufacturing cost of the antenna will be increased.
Further, the terminal face 21a of the joint assembly 21 is pressed by the terminal 21b of the antenna base 21 by the elasticity of the coil spring 23, thereby frictionally slides on the terminal 21b of the antenna base 21 by the elasticity of the coil spring 23, and transmits the antenna signal. With this structure, the hemispherical convex portions 211, 211, and 211 formed in the terminal face 21a of the joint assembly 21 is pressed with strong force of the coil spring 23 on the terminal 12b. 
The hemispherical convex portions 211, 211, and 211 thus will be easily worn by the clicks, and the lifetime of the hemispherical convex portions will be shortened extremely if the mounting angle of the antenna rod 11 is changed so frequently.
In addition to the problems mentioned above, the assembling process of the antenna is so complicated as shown in FIG. 2. In the assembling process, the click case assembly 25 into which the coil spring 23 is inserted needs to be introduced into the hexagonal hole 12a from the outside such that the convexes and recesses formed on the outer circumferential surface of the click case assembly 25 are engaged with the recesses and convexes formed on the inner circumferential surface of the joint assembly 21, and then the bolt 22 is inserted. Then, the bolt 22 penetrating the hexagonal click plate 27 is inserted such that the hexagonal click plate 27 is properly put into the hexagonal hole 12a till the end tip of the bolt 22 projects from the outer wall of the terminal 12b. Consequently, the structure mentioned above lowers the assembling efficiency so much.
The present invention is carried out to solve the above-mentioned problems, and an object of the present invention is to provide a pivottable connection configuration of a retractable roof mounted antenna by suppressing the increase of the manufacturing cost of the components, improving the assembling efficiency, and lengthening the lifetime of the antenna.
The pivottable connection configuration of a retractable roof mounted antenna, which has an antenna rod and an antenna base for rotatably supporting the antenna rod, according to the present invention is characterized by comprising: a joint portion provided to one end portion of the antenna rod, the joint portion having a cylindrical member with a bottom and a rotation axis orthogonal to an axis of the antenna rod, the cylindrical member having a first and second surfaces perpendicular to the rotation axis, the first surface having one of recess and convex portions for generating click resistance, the second surface having a terminal surface electrically connected to the antenna rod; a pair of supporting portions comprising a first and second supporting portions formed in an upper portion of the antenna base so as to surface each other, the first supporting portion having a through hole, the second supporting portion having a terminal portion electrically connected to the terminal surface of the joint portion on an inner surface facing to the through hole; and a click cylinder having one of convex and recess portions to be engaged with the one of the recess and convex portions of the first surface of the cylindrical member.
It is preferable to further comprise a coil spring to be introduced into the click cylinder and a washer introduced into the through hole, and is preferable that the washer is engaged with the first supporting portion such that rotation on an a supporting axis of the first and second supporting portions is controlled.
It is preferable to further comprise a wave washer contacting an outer surface of the second supporting portion; a bolt passing through the members and the portions comprising the pivottable connection configuration; and a nut for screwing the bolt.
With this structure, click torque is generated between the inner surface of the bottom face of the joint assembly and the outer face of the bottom face of the click cylinder by virtue of the elasticity of the coil spring. In the same time, the outer face of the bottom of the joint assembly is frictionally contacted with the terminal portion on an inner face of another one of the supporting portion by virtue of the elasticity of the wave washer, and the electric connection for transmitting the antenna signal can be obtained thereby. With this structure, the portion for generating the click resistance and the portion for transmitting the antenna signal can be formed as an integral component, and thus all the metal components necessary for the structure of the present invention can be manufactured in a presswork or the like. With the result, the manufacturing cost of the components can be reduced so much.
Further, this structure need no conventional complicated assembling such that the coil spring must be pressingly held and the components are positioned to be penetrated by the bolt and then the bolt must be screwed with the nut. Accordingly, the assembling process can be considerably simplified in comparing with the structure of the conventional pivottable connection configuration, and thus the assembling efficiency can be remarkably improved.
In addition, since a member with low elasticity can be employed as the wave washer, the terminals can be electrically connected without so large click torque. Accordingly, the recess and convex portions for generating the click resistance can be prevented from being worn by large click torque, and thus the lifetime of the antenna can be lengthened even if the antenna rod is rotated so frequently.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.